Purpose There is robust evidence for offering supported self-management interventions for people with severe mental illness (SMI) throughout secondary mental health services, but their availability remains patchy. The aim of this systematic review is to synthesise the evidence on barriers and facilitators to implementing self-management interventions for people with SMI in secondary mental health care settings. Methods The review protocol was registered with PROSPERO (CRD42021257078). Five databases were searched to identify relevant studies. We included full-text journal articles with primary qualitative or quantitative data on factors which affect the implementation of self-management interventions for people with SMI in secondary mental health services. The included studies were analysed using narrative synthesis, using the Consolidated Framework for Implementation Research and an established taxonomy of implementation outcomes. Results Twenty-three studies from five countries met eligibility criteria. The barriers and facilitators identified in the review were mainly on the organisational level, but included some individual-level influences. Facilitators included high feasibility, high fidelity, a strong team structure, sufficient number of staff, support from colleagues, staff training, supervision, the presence of an implementation champion and adaptability of the intervention. Barriers to implementation include high staff turnover, staff shortage, lack of supervision, lack of support for staff delivering the programme, staff struggling with their increased workload, a lack of senior clinical leadership, and programme content perceived as irrelevant. Conclusion The findings from this research suggest promising strategies to improve implementation of self-management interventions. For services providing support for people with SMI, organisational culture should be considered, as well as the adaptability of interventions.